What makes Gwyneth Paltrow the world's most beautiful woman?

IT IS a question that is both impossible to answer and about which everyone has an opinion: who is the world's most beautiful woman? Yet according to an American magazine survey, that honour goes to Gwyneth Paltrow.

The actress, 40, married to Coldplay singer Chris Martin with whom she has two children, played down her new description, insisting: "It's very sweet but obviously not true."

For many observers, however, a combination of features do indeed make her one of the great beauties of her time. Here's why.

FACE The symmetry of Gwyneth's is one of her greatest attributes. Science writer Jena Pincott, author of Do Gentlemen Really Prefer Blondes?, explains: "She is a perfect example of a beautiful but slightly atypical face. Her mouth is wider than average and so is the space between her eyes.

"On another person these distinctive features might not be so stunning but Gwyneth's face happens to be perfectly symmetrical. Symmetry often plays a role in attractiveness as it suggests a certain physical robustness."

Researchers at the University of New Mexico took measurements to determine the facial symmetry of 400 men and women. They found that people with the most symmetrical features were healthier.

The actress's complexion is also praised. "Gwyneth's pale northern European skin tone has yellow undertones, rather than red or blue," says Julia Francis, make-up artist and consultant. "A yellow skin tone is the most flattering for make-up and clothes. Those with red or blue undertones have a harder time.

"She also has incredibly porcelain skin which is an indicator of a very healthy diet and the fact she probably drinks a lot of water."

"She eats organic vegetables with a little meat and no grain. Gwyneth's skin looks clearer because her body isn't having to work hard to remove toxins from the food she eats."

HAIR "Research shows that in most of Europe and America there seems to be a male preference for blonde women," says Jena Pincott. "Blonde hair is associated with youth and fertility as hair darkens with age."

EYES "The whites of Gwyneth's eyes are amazingly white, which is very rare," says anti-ageing expert and skincare designer Star Khechara. "Due to pollution and poor diet, most people's eyes are somewhat bloodshot. Hers are very clear, which makes the iris really stand out in contrast and draws you in. The eyes are not only the windows to your soul but a key indicator of health."

Julia Francis says the actress's eyes have an added boost. "Gwyneth has a natural arch in her brow which is very attractive," she says.

BODY "Gwyneth is in great shape and has excellent posture and poise," says Matt Roberts, celebrity personal trainer. "She is clearly very lean. This comes from a combination of regular exercise and eating food that is very fat controlled. She looks as if she does a fairly high amount of fatburning cardiovascular work. "The fact she has no muscle bulking suggests that she does low resistance calisthenics based on dance-style movements. Pilates has also given her great core strength and posture."

Peter Spalton, known as the Dating Doctor, who offers courses in body language and self-presentation, claims: "Gwyneth has great posture that makes her look confident and approachable.

"She stands tall, with shoulders back, stomach in and head held high. She knows she looks good and she's comfortable with it."

Jena Pincott says that another of Gwyneth's secrets is her waist-to-hip ratio. "This is one of the most important cues in sexual attraction," Jena explains. "Gwyneth has the 'golden ratio' said to be around 0.7 - that is, a waist that is seven-tenths the width of the hips, regardless of weight."

Gwyneth Paltrow has a stunning set of perfectly white teeth

She knows she looks good and she's comfortable with it

Science writer Jena Pincott

SMILE "Her smile is a killer weapon," says Peter Spalton. "It's a genuine one that makes her eyes shine and her entire face sparkle. It is very disarming."

Julia Francis adds: "She has a wonderful set of perfectly white teeth that are all visible when she smiles, rather than being partially obscured by the lips. This is a huge advantage in making a face look its best."

PERSONALITY "Gwyneth has an appealing calmness and positivity that makes her very attractive," says Seven Suphi, author of Authentic Catalyst: Fast Track To Behavioural Change. "She has high self-worth and believes in herself which is the main ingredient you require to be truly beautiful.